Computer devices are becoming ever smaller and full computing functionality can be found on phones and smart phones and other personal digital assistants (FDA). As the computer devices become smaller, the various features of the computer devices may also become smaller. This includes a desire for smaller input systems for the user to enter inputs into the device. One such input system is an optical navigation device. Many computer devices, large and small, are equipped with optical navigation devices. However, with the smaller computer devices, minimizing the size of the optical navigation device can often be restrictive and problematic.
A number of devices have been proposed which offer thin optical navigation devices. These have had some success but the design has generally not addressed all of the problems associated with thin imaging devices. One such outstanding problem is associated with the positioning of the sensor. Ideally the sensor is located as close to an imaging surface of the imaging device as is possible. This can be achieved by de-centering the sensor. However, this may then give rise to distortion such as perspective distortion, in the image generated at the sensor. In addition, such de-centering of the sensor can cause problems with shielding the sensor from any stray light which enters the imaging surface.
In professional and architectural photography, perspective control lenses exist. These may require considerable space for the design which incorporates the ability to tilt and de-center the input lens to correct for any perspective effect. However, the requirement of greater space may be undesirable in small-scale optical navigation devices.